1. Field of the Invention
The invention involves a classifying equipment for unequal particles of the same kind or the same density, specially involves a screenless vibratory separator.
2. Description of the Related Art
Screen technique is actually a grading classification according to granularity of particles. Up to now screen equipments and techniques are all based on the knowledge of the related objects. For bulk-variant solid particles a screen with mesh is usually adopted. It essentially utilizes the norm of mesh holes to pick out particles, which leads to low separating efficiency for the reason given below. First of all, the internal forces, namely the effects of galling, dampness and electrostatic force caused by tight material, increase the resisting force through mesh holes. Moreover, under the restriction of mesh holes the particles can only pass through one by one. So the capacity and the speed is largely limited. A vibratory screen with mesh takes advantages of higher efficiency than traditional one without vibration. Typically, it consists of a vibrating screen with mesh, a vibrator and a support system. Vibrating improves the condition that particles get through mesh holes, thus increases the operating efficiency. This makes a great progress relative to the tradition type. However, it doesn't give up the basic principles of screen with mesh, so can't overcome its inherent shortcomings.
All kinds of screen with mesh suffer a great deal of restriction in application because one norm of mesh can only meet the case of one granularity. To classify particles with different granularity, different screen surfaces must be used. To realize it at the same time, multi-screen or combination of screen surfaces must be considered Obviously, this sophisticates the industrial art, raises the costs. What's more, choke, especially in the case of small particles and small mesh holes, often interrupts production, which greatly lowers the efficiency, even disables the screening. The vibratory screen with mesh that makes use of water or air as medium can make up for most of these shortcomings. But the complexity of mechanical structure, the high cost, the waste of water and the fact that some material doesn't fit to be soaked all limit its application. What's worst, breaking of mesh holes usually makes all the previous screen sizing performed by such setup with mesh wasted.
In the mineral-dressing industry, a concentrating machine without mesh is commonly used. For instance, jiggers, both the wind power jigger and the waterpower one, utilize the character rooting in different density, thus separate material of different density. But it can't separate particles according to their granularity. Therefore, strictly sealing, such sieving equipments as jiggers are just accumulating equipments, not screening ones, and can only be applied to special fields.
U.S. Pat. No. 3,472,379 describes a stratifying technique for material, which includes a separating equipment composing of an oblique slot, a vibrator and a support. When operating, the input of the slot does a peripheral motion in a plane and the outlet does a horizontal motion to stratify particles of low density into the upper layer and particles of high density into the lower one as a result of gravity. It's specially pointed out that the technique and equipment can only separate rubber, fiber and similar material with density difference of about 3-4 times. So the application is quite limited In particular, the stratifying technique can't also separate particles by their granularity.
In the industrial and agricultural production, screen by granularity is most necessary. And the foreground is very promising. Therefore developing a new screen equipment with wide application, high efficiency, simply suture and high reliability to overcome the shortcomings of traditional separating techniques and equipments makes an extremely practical sense.
Screen by granularity essentially classifies particles of the same kind or the same density according to the size. Based on this cognizance, we invent a screenless vibratory separator.